Cold working metal bar



March 4, v1941. E. LUKAcs COLD WORKING METAL BARV 2 Sheets-Sheet 1- Filed Jan. 13, i939 Il [u 3 Il.

,4 fr0/PNE Y6 2 sheets-sheet 2 Filed Jan. l5, 1959 A TTORNEYS Patented Mar. 4, 1941 1 PATENT OFFICE 2,233,869 COLD WORKING METAL BAR Ernst Lukcs, Budapest, Hungary Application January 13, 1939, Serial No. 250,737 In Hungary October 9, 1937 6 Claims.

My invention relates yto metal bars `and more particularly to a method -of an apparatus for cold working round, or nearly round, metal bars of commercial quali-ty, such as round iron rods, by means of twisting.

The expression "round or nearly wund metal bars used hereinafter, does notl include bars provided with projections such as ribs, for example section or profiled iron, and the invention is not to be construed as including the Vtreatmc-znt of such bars.

In .the case of most metals, when they are worked in the cold state, without removing particles of matter, in such a way that lthe individual particles'of matter are mutually displaced, it is known that ,the yield point and tensile strength are raised, while stretching is lowered. Such working is of particular importance in the case of the ordinary round iron rods of commerce which are-embedded in a foreign medium, such as concrete, and subjected to tension.

The degree of working, and hence the raising of the yield point and so on, could not hitherto be ascertained from iron rods so worked: I-t was therefore necessary to proceed very carefully when usnig iron rods treated in this manner, so that the stressing to which they were subjected gener-ally remained far below .the permissible The object of my invention is .to provide cold worked iron rods with markings indicative of the the other until they undergo permanent deformartion.

I provide the round or nearly round metal bar, such as a round iron rod, to be worked by means of twisting, either before or at the same time as it is so worked, with a marking which represents, after the working, a pattern in the shape of a helical line, the pitch of which is substantially inversely proportional to the degree of working, while this proportion may be either linear or non-linear.

My invention may, for example, be carried out by providing on the metal bar, before it is worked, small impressions, such as fiuting or milling, running parallel to the axis of said bar, which assume vthe form of 'a helical line when the bar undergoes twisting. The impressions may n-aturally be replaced by any other desired markings, for example coloring or the like. The pattern which appears Iafter .the working may be of any type, while any two points can be fixed on the pattern lbetween which the pitch of lthe helical 10 line is measured.

The advantage of my method consists in that patterns are produced on the outer surface of .the metal bar which enable the yield point and ytensile strength of the bar .to be deduced with certainty. My method also affords the additional advantage that the regularly distributed uneven Iportions of the surface of the pbar substantially increase .the adhesion of the ir-on rod in the embedding medium, such as concrete.

Various apparatus can be employed for carrying out the method of the invention, i. e. for twisting .the iron rod .and marking `the degree of torsion, and of these the following will be described byway of example:

The metal bar is drawn through a pair 4of loaded rolls, one or both of which are grooved. or through a grooved tool, and then one end of the bar is gripped in a stationary jaw while the other end 'is turned until ythe desired increase in lthe yield point has taken place. The degree of f torsion-can be measured with a revolution counter, which in turn can be coupled, if desired, with a per se known automatic disconnecting device, by -which the-apparatus used for twisting the bar is automatically disconnected when the desired screw pitch is attained.

The metal bar is passed between rolls, one or. both of which are grooved and lthe axes of which are not parallel, being drawn therethrough either on a draw bench, by means of gripping pliers, or with the aid of a pair of rolls. The gripping pliers should not perform any rotary movement.

'I'he metal -bar is drawn lthrough a pair of drivenI rolls one or both of which are grooved and which also lperform a planetary movement about the axis of ythe bar, while in this case also the barv can be drawn therethrough with the aid of gripping pliers or of a' pair of rolls. r

In order that the invention may be more clearly understood, reference is made to the accompanying drawings, in which:

Fig. 1 is a diagrammatic side elevation of one embodiment of my apparatus;

' ythe line II-II of Fig. 1;

Fig. 3 is a View of a marked metal bar before the twisting operation;

Fig. 4 shows .the same bar after the twisting operation;

Fig. 5 is a side elevation of -a second embodiment -of my apparatus;

Fig. 6 is atop view of the same;

Fig. 7 is a side elevation, partly in section, of

a .third embodiment of my apparatus;

Fig. 8 is a top view of the same;

Fig. 9 lis a characteristic curve showing the improvement of .the mechanical properties as a function of the degree of twist.

In Figs. 1 and 2 is shown the simplest form lof the apparatus, in which a pair of rotary rolls, consisting of a grooved upper vroll I and an even lower roll 2, is employed, the upper roll I being mounted with'its axis I1 in a pair of levers I 8 pivoted at I9 on a bracket 20 constitutinga part of the supporting frame 2|. 'I'he levers I8 support a weight 3, so that the upper roll I is constantly pressed against the lower roll 2. The

axis 22 of the lower roll 2 is rotatably mounted in stationary bearings 23 which form a part of the frame 2l. If a round iron rod g be now drawn through the pair of said rolls inv any desired direction, the groovings provided on the upper roll will be impressed into the iron rod, as shown in Fig. 3.' In the marking apparatus shown in Figs. 1 and 2, a pair of rolls 24, 25 are used to move the rod g forward between the marking rolls I and 2. The forwarding rolls 24, 25 are rotatably mounted in alignment with the marking rolls I and 2, the lower roll 25 having stationary bearings, while the upper roll 24 is journaled in a bearing block 42 which is slidably mounted in the frame 2| and is engaged by a coiled spring 26, the tension of which may be adjusted by a set screw 21. The rolls 24 and 25 are rotated with equal peripheral speeds by toothed wheels 24' and 25', respectively, which mesh with one another and with a pinion 28 driven by a motor not shown in the drawings. If the rod g which leaves the apparatus shown in Figs. 1 and 2 with the marking i impressed upon it (Fig. 3), is then subjected to torsion until permanent deformation takes place, the impressed depressions i on the surface of the iron'rod will form a pattern running in the form of a helical line, as will be apparent from Fig. 4. The pitch e of the helical line is substantially inversely proportional to the degree of working and can be limited with the aid of an automatic disconnecting device.

In the embodiment illustrated in Figs. 5 and 6, theiapparatus comprises gripping pliers 5 and grooved rotary rolls 6, 1, the axes 8, 9 of which are not parallel to one anotherbut lie in parallel planes. The axes 8 and 9of the rolls 6 and 1 are journalled in bearing blocks 29 and 30, respectively, said blocks beingslidably mounted in the supporting frame 3| and carried by adjustment screws 32 extending through openings formed in the frame 3| and having inner screw threads. The screws 32 are rotatably connected with the bearing blocks 29 and 30. By turningthe adjustment screws 32, the rolls 6 and' 1 may be pressed against the rod y. Gripping pliers 5 are then used to move the rod forward between-the rolls. In order to prevent pairs of lateral rollers 36 between two stationary guide rails 31, which are U-shap'ed in cross-section. The block 35 is drawn by a chain 38 in the direction of the arrow I0, so that it moves in the longitudinal direction of the rod g. When the rod is thus drawn between the rolls 6 and 1 and is wedged between them with suitable pressure, it will be subjected to a torsion which is proportional to the inclination of the roll axes to one another. 'I'he grooving on the rolls 6, 1 is impressed into the iron rod, so that patterns running in the form of a helical line will be produced on the iron rod. The pitch of the helical line is once again substantially "inversely proportional to the deformation of the iron rod, i. e. to the degree of torsion.

Finally, the apparatus inthe example shown.

in Figs. 7 and 8 consistsoi gripping pliers Il and a grooved upper roll .I2 and an even lower roll I3, theaxes I4, I5 of which are parallel and which, in'addition to their rotation about their own axes, also revolve about the axis of the iron rod g. For this purpose the rolls. are mounted in a trunnioned frame I6 rotatably mounted in a pedestal I1. The trunnions 39 of the frame I6 are hollow, so that the rod g can be moved through them to and from the rolls I2 and I3. The frame I6 is rotated by a toothed wheel 40 which is xed upon one of the trunnions 39 and meshes with a pinion 4I. The pinion 4I is journaled in the pedestal I1 and is driven by a motor not shown in the drawings. 'I'he gripping pliers Il as well as other elements drawing the rod between the rolls I2. and I3 are identical to those provided in the device illustrated in Figs. 5 and 6 or the drawings. If the iron rod g be nowpdrawn by means of the gripping pliers I I (or by means of a pair of rolls) between the rollsv I2, I3, in the direction of the arrow I8, it will undergo torsion in a similar way as in the example shown in Figs. 4 and 5, and at the same time patterns in the form of a helical line will be produced on its surface and will be indicative of the degree of torsion.

The raising of the yield point or of the tensile strength can be represented, as shown in Fig. 9, in the function of al fraction e/D, the numerator e of which represents the pitch ofy thefhelical line appearing after the working and the denominator D or which represents the diameter of same diameter D the pitch e of the helical line decreases.

The method of the invention is also suitable for ymarking round or nearly round metal bars the tensile strength of which varies in the di-frection of the length by twisting the bar according to a helical line of varying pitch, for example with the aid of the apparatus illustrated in Figs. 5 to 8, the pattern appearing on the surface of the bar after the working automatically and immediately indicating the varying tensile strength. On the contrary, variation of the pitch vof the helical line along a. bar which has been twisted in a uniform manner throughout its lengthindicates that the bar was originally defective, i. e. of varying resistance against torsional stress.

I claim:

1. In a method of cold working roundish metal l bars by twistingthe step oi' fumishing thesurbars by twisting, the step of furnishing the surface of the bar with impressions s6 runningin longitudinal direction as to extend on the twisted bar along a helical line'. the pitchof which is characteristic of the degree of working bestowed by twisting. l A

' 3. In a method of coldworking roundish metal bars by twisting, the step of furnishing the surfacev of the bar before the twisting operation with a marking runningparallel to the axis of the bar so as to extend on the twisted bar along a helical line', the pitch of which is characteristie of the degree of working bestowed by twisting.

4. Iny a method of cold working roundish metal bars' by twisting, the step of furnishing the sur- 20 face of the bar before the twisting operation with impressions running parallel to -the axis of tll'e bar so as to extend on the twistedl bar along a helical line, the pitch of which is characteristic of the degree of workingbestowed by twisting.

5. In a. method of cold Working roundish metal bars by twisting, the step of furnishing the surface of the bar simultaneously with the twisting operation with` a marking so nmning in longitudinal direction as to extend on the twisted bar along a helical line. the pitch of whichV is, characteristic of the degree of working bestowed by twisting.

6. In a method of cold working roundish metal bars by twisting, the step of furnishing the surface of the bar simultaneously with the twisting operation with impressions so running in longitudinal direction as to extend on the twisted bar along a helical line, the pitch of which is char acteristic of the degree of working bestowedby twisting. u

ERNST LUKCS. 

